All science is materialistic

[LinuxGal]

A particle is fundamental when it is determined to have no constituents.

An electron, for example, is fundamental, while a proton, made of (fundamental) quarks and gluons, is composite, even though energetically a proton has no decay channel (under the Standard Model at least, if not under assorted proposed extensions to the SM).

Fundamental implies that the chain of inquiry has terminated.  The masses of fundamental particles (if they have masses) are simply brute empirical facts.  This makes for an unwieldy theory, but it's the best we have.

Which, again, does not address the question of what it means to be 'matter' or 'material'.

A photon is fundamental, but is usually NOT considered to be matter (it isn't made of atoms, for example), while it *is* physical. Muons are usually regarded as fundamental as well (although they decay into electrons and neutrinos), but are not considered by most to be 'matter' even though they are fermions.

Whether electrons and quarks are truly fundamental is still in question. There are theories that have quarks as composite particles. To say that the chain of inquiry has terminated says that science has nothing further to say, which is almost never the case.

For example, are electrons and muons simply resonance states of the same particle? Is there a symmetry between fermions and bosons?

Ultimately, whether photons and other bosons are labeled as 'matter' or not is pretty irrelevant. Science is based on using observation to test our ideas. There is no required assumption that all explanations are in terms of matter or even physical things. But there *is* an expectation that all ideas have testable results.

Whether photons are matter or not sounds like the question whether Pluto is a planet or not.  Photons curve space and they can cause a solar sail to accelerate through recoil, which is material enough for government work. Physics is about cataloguing what is.  Photons are.  They are physical, just as Higgs particles and gluons are. But there is an expectation they are essentially different from matter because when a positron and electron annihilate each other all you have left is photons. Then again, we know in high energy collisions this works the other way around, and photons can be intermediate states between colliding protons and any number of other particles, maybe like this: